1. Field of the Invention
The present invention relates to a resist composition suitable for use in the ultramicrolithography process such as production of VLSI or high-capacity microchip or in other photofabrication processes, and a pattern forming method using the composition. More specifically, the present invention relates to a resist composition capable of forming a high-resolution pattern by using electron beam, X-ray, excimer laser or the like, and a pattern forming method using the composition.
2. Description of the Related Art
The electron beam lithography is positioned as the next-generation or next-next-generation pattern formation technique, and a resist assured of high resolution and good line edge roughness is strongly demanded.
As regards the resist for electron beam or X-ray, the resist technique for KrF excimer laser has been heretofore mainly utilized and studied. For example, there are disclosed a combination of a compound capable of generating an acid upon irradiation with electron beams and an amine compound having a boiling point of 250° C. or less in JP-A-2000-181065 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”), a combination use of an acid-decomposable group-containing polymer, an acid generator and an electron beam sensitizer in European Patent 0919867, and a combination use of an amide compound in JP-T-7-508840 (the term (the term “JP-T” as used herein means a “published Japanese translation of a PCT patent application”). Furthermore, JP-A-3-200968 discloses use of a maleimide compound, JP-A-7-92680 discloses use of a sulfonamide compound, and JP-A-11-44950 discloses a sulfonimide compound containing an —SO2—NH—SO2— partial structure. However, in all of these attempts for improvement, both high resolution and good line edge roughness cannot be satisfied at the same time. The edge roughness as used herein means to have an appearance such that due to properties of the resist, the edge at the interface between the resist line pattern and the substrate is irregularly fluctuated in the direction perpendicular to the line direction. When this pattern is viewed from right above, irregularities are observed on the edge. These irregularities are transferred to the substrate in the etching step and if the irregularities are large, this causes electrical characteristic failure and reduction of the yield.
In this way, conventionally known combinations can hardly realize both sufficiently high resolution and good edge roughness under irradiation with electron beams or X rays, and it is strongly demanded to satisfy these two properties at the same time.
Formation of an ultrafine pattern of 0.20 μm or less is targeted also in the lithography using short-wavelength excimer laser light such as KrF or ArF for the exposure light source, but it is impossible to satisfy both the resolution and the sidelobe margin at the same time, and a resist composition capable of simultaneously satisfying these properties is strongly demanded.